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FM-100 question

grindfix

grindfix

Full time hobby
Subscriber
I picked up this tuner last weekend and have a question. It does not have MPX adapter. Is it suppose to output only through one channel or should still output mono in both channel outputs? Two schematics I found have different MPX adapter models but not showing circuit jumpers for use without MPX.
Thanks for your help!
 
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With the dummy plug installed and the selector switch turned to FM Mono, there will be Mono FM present at the output of Channel A, adjustable by the Channel A Level Set control. Also at that setting, the output of Channel B is whatever might be presented to the Channel B Ext(ernal) input -- this almost surely being back in the day an AM tuner, so that in this setting, the old FM/AM stereo broadcasting format could be received -- FM in the left channel, AM in the right.

Dave
 
Thanks Dave! I was looking at the wrong schematic and did not notice that it was for FM100-C. Pin 7 of dummy connector has no input. Got it!
What MPX adapters would work with this model?
 
It was originally designed to work with the MPX-20 Crosby detector, but when that method was not approved, Fisher had to scramble and come out with the MPX-50. It's a rare piece and does not have the performance of the latter more common units, but that is the model the FM-100 was designed to work with.

Dave
 
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